I was elected to Leeds city council during the miners' strike, perhaps the defining domestic event in her period of office and I became leader in 1989. I was there when she left office having tackled head-on her assault on local government and communities, most notably the poll tax.

All who were politically aware, as I was, at the end of the 1970s understood the relevance of WB Yeats' celebrated line "Things fall apart; the centre cannot hold".

The postwar settlement introduced by Labour under Attlee was under increasing strain, partly as a consequence of a fiscal crisis brought about by the falling profitability of British capitalism. First Heath and then Wilson and Callaghan sought to maintain the 1945 consensus. By the end of the Callaghan government Labour's leaders were exhausted physically and intellectually, as brilliantly captured in the play This House which is currently showing at the National in London. Britain was trapped in an impasse. Something had to give. Gramsci had described such a moment as an interregnum. In our country, "the past was dying; and the new cannot be born".

The 1979 election could not be like the others and the same is true of 2015. It had to be a moment of rupture in order to break the sclerotic British structures. Of course, we were aware that nothing in politics is certain. For the left, the solution was clear and, many thought, inevitable. Britain should move beyond the Attlee consensus and into a more socialist society.

But when a country arrives at a turning point, as we clearly had, the direction that it takes is not pre-determined.

Thatcher had understood all of this too. As we now know, it was she who ended the interregnum into which the country had fallen.

She broke with the Attlee consensus and created a new settlement that has endured (albeit modified by New Labour) ever since. Thus it was possible for Tony Blair to say – in his comments immediately in the aftermath of Thatcher's death – that: "I always thought my job was to build on some of the things she had done rather than reverse them." But this Thatcher-introduced settlement is now under pressure as never before.

Indeed, we can now see how Thatcherism contained a systemic design flaw. The certainty of the 2008 crisis was built into the post-1979 system. The ideas of market triumphalism meant that the normal process of government intervening in the economy to protect the wider community interests was suspended.

The country was treated to reduced regulation of an increasingly dominant financial sector without the counterweight of a strong manufacturing sector. And it was the failure properly to regulate finance capitalism that was precisely what was at the heart of the crash.

All elections are in part a contest between continuity and change. But the next election cannot be about more of the same: a further modification of the existing economic settlement.

What is needed is a rupture with the last 30 years. But the question is which way should this rupture take Britain?

Even a brief glance at the political landscape reveals that the Tories and Lib Dems have chosen to respond to the crisis by seeking further intensification of all the characteristics of the Thatcher consensus. Thus we see austerity, more marketisation, a further assault on the public domain, growing inequality and so on. If this path prevails, then we can be sure that our economy will flatline for the foreseeable future and that a further crisis is inevitable.

Both the Tories and the Liberal Democrats are hopelessly compromised by their period in office. The Tory modernisation project has been jettisoned partly due to the threat from Ukip, and the Lib Dems have irrevocably embraced divisive neoliberal economic and social reform (such as the NHS reforms).

Therefore, if there is going to be a government that will usher in a fresh start for Britain it will be the Labour party.

Ed Miliband has shown that he understands the historic task that falls to the party and his leadership. Last year he said:

"Consent for the old system has broken down … But anger at the old system's flaws is not enough to produce change. It needs the ideas and the political movement to transform discontent with the old settlement into consent for the new one."

Thatcher fully understood the power of ideas and while in office and in opposition she carefully nurtured the growth of a new paradigm. When in office there was a steely determination on her part to bring about change. Thus, although there was no single moment of rupture with the Attlee consensus there was a remorseless process change so that by the time she left office our country's economic and social systems were configured in a way that endured through to the present day.

Labour's task is no less than to create a vision of a new way of governing Britain. We need to build a movement that is capable of sustaining a one-nation Labour government of a new kind.

We will need steely nerves, inventive imaginations and new ways of communicating and governing. With only two years left, there is much work still to be done.